The present invention relates to a method for controlling the stepping feed of an information medium such as a magnetic tape used in a mass storage system (which is called an MSS).
In recent years, as data processing systems have developed, the amount of data to be processed has increased rapidly. This data is usually stored on magnetic disks or magnetic tapes during and after processing. These magnetic disks or magnetic tapes are often kept in a storehouse or the like due to the limited size of the installation space. However, it is necessary to have access to large amounts of data for on-line operations. Therefore, as occasion demands, the magnetic disks or magnetic tapes on which the data is stored must be taken out of the storehouse or the like and mounted on a data access device. Accordingly, there are many problems regarding the custody and mounting of the magnetic disks or tapes.
In order to solve the above-mentioned problems, an MSS by which large amounts of data can be under the control of the system has been developed. The information medium used in the MSS is called a data cartridge which is comprised of a magnetic tape approximately 7 cm wide and 20 m long housed in a cylindrical shell approximately 5 cm in diameter and 9 cm long. The data cartridge storage capacity is, for example, 50M bytes, and 706 to 9440 data cartridges can be stored in one MSS. When a data cartridge is needed by the data processing system, the data cartridge is carried by an accessor from the storage area to the data accessing device, and then data processing is performed on the data cartridge. Recording tracks on the magnetic tape are stripes which run diagonally across the tape. Track positioning of a magnetic head is performed by a servo mechanism. The present invention relates to a method for controlling the stepping feed of such a magnetic tape by the amount of one stripe.
One conventional method for controlling the stepping feed of a magnetic tape comprises the steps of: recording or reading data on a recording track; checking the recorded or read data on the recording track; if no error is detected as a result of the checking, feeding the magnetic tape by the amount of one stripe so as to record or read data on the next recording track; and if an error is detected as a result of such checking, recording or reading the data again on the recording track. However, in this conventional method, since the feed operation of the magnetic tape cannot be started until the checking of recorded or read data is completed, it takes a substantial amount of time to feed the magnetic tape; in other words, there is a disadvantage in that the the data transfer rate is slow.